| performance of batch, fed-batch, and continuous a-b-e fermentation with ph-control. | batch, fed-batch, and continuous a-b-e fermentations were conducted and compared with ph controlled at 4.5, the optimal range for solvent production. while the batch mode provides the highest solvent yield, the continuous mode was preferred in terms of butanol yield and productivity. the highest butanol yield and productivity found in the continuous fermentation at dilution rate of 0.1h(-1) were 0.21 g-butanol/g-glucose and 0.81 g/l/h, respectively. in the continuous and fed-batch fermentation, ... | 2010 | 21227684 |
| butanol production under microaerobic conditions with a symbiotic system of clostridium acetobutylicum and bacillus cereus. | one major problem of abe (acetone, butanol and ethanol) fermentation is high oxygen sensitivity of clostridium acetobutylicum. currently, no single strain has been isolated or genetically engineered to produce butanol effectively under aerobic conditions. in our previous work, a symbiotic system tsh06 has been developed successfully by our group, and two strains, c. acetobutylicum tsh1 and bacillus cereus tsh2, were isolated from tsh06. | 2016 | 26762531 |
| switching clostridium acetobutylicum to an ethanol producer by disruption of the butyrate/butanol fermentative pathway. | solventogenic clostridia are well-known since almost a century due to their unique capability to biosynthesize the solvents acetone and butanol. based on recently developed genetic engineering tools, a targeted 3-hydroxybutyryl-coa dehydrogenase (hbd)-negative mutant of clostridium acetobutylicum was generated. interestingly, the entire butyrate/butanol (c(4)) metabolic pathway of c. acetobutylicum could be inactivated without a severe growth limitation and indicated the general feasibility to m ... | 2011 | 21549853 |
| a novel combinatorial biocatalytic approach for producing antibacterial compounds effective against mycobacterium tuberculosis (tb). | two bacterial hosts expressing cloned aromatic oxygenases were used to catalyze the oxidation and polymerization of indole and related substrates, creating mixtures of indigoid compounds comprised of novel dimers and trimers. crude extracts and purified compounds were tested for their ability to inhibit the growth of gram-positive organisms, in general, and mycobacterium tuberculosis (tb), in particular. of the 74 compounds tested against m. tuberculosis, ~66 % had minimum inhibitory concentrati ... | 2013 | 23749163 |
| kinetic isotope effects and hydrogen/deuterium exchange reveal large conformational changes during the catalysis of the clostridium acetobutylicum spore photoproduct lyase. | spore photoproduct lyase (spl) catalyzes the direct reversal of a thymine dimer 5-thyminyl-5,6-dihydrothymine (i.e. the spore photoproduct (sp)) to two thymine residues in germinating endospores. previous studies suggest that spl from the bacterium bacillus subtilis (bs) harbors an unprecedented radical-transfer pathway starting with cysteine 141 proceeding through tyrosine 99. however, in spl from the bacterium clostridium acetobutylicum (ca), the cysteine (at position 74) and the tyrosine are ... | 2017 | 27992649 |
| zero-power autonomous buoyancy system controlled by microbial gas production. | a zero-power ballast control system that could be used to float and submerge a device solely using a gas source was built and tested. this system could be used to convey sensors, data loggers, and communication devices necessary for water quality monitoring and other applications by periodically maneuvering up and down a water column. operational parameters for the system such as duration of the submerged and buoyant states can be varied according to its design. the gas source can be of any orig ... | 2011 | 21639539 |
| construction of a restriction-less, marker-less mutant useful for functional genomic and metabolic engineering of the biofuel producer clostridium acetobutylicum. | clostridium acetobutylicum is a gram-positive, spore-forming, anaerobic bacterium capable of converting various sugars and polysaccharides into solvents (acetone, butanol, and ethanol). the sequencing of its genome has prompted new approaches to genetic analysis, functional genomics, and metabolic engineering to develop industrial strains for the production of biofuels and bulk chemicals. | 2016 | 26839586 |
| 1,3-propanediol production in a two-step process fermentation from renewable feedstock. | in this work, the production of 1,3-propanediol from glucose and molasses was studied in a two-step process using two recombinant microorganisms. the first step of the process is the conversion of glucose or other sugar into glycerol by the metabolic engineered saccharomyces cerevisiae strain hc42 adapted to high (>200 g l(-1)) glucose concentrations. the second step, carried out in the same bioreactor, was performed by the engineered strain clostridium acetobutylicum dg1 (pspd5) that converts g ... | 2011 | 21656140 |
| diverse mechanisms regulate sporulation sigma factor activity in the firmicutes. | sporulation allows bacteria to survive adverse conditions and is essential to the lifecycle of some obligate anaerobes. in bacillus subtilis, the sporulation-specific sigma factors, σ(f), σ(e), σ(g), and σ(k), activate compartment-specific transcriptional programs that drive sporulation through its morphological stages. the regulation of these sigma factors was predicted to be conserved across the firmicutes, since the regulatory proteins controlling their activation are largely conserved. howev ... | 2015 | 25646759 |
| characterisation of a glucosamine/glucosaminide n-acetyltransferase of clostridium acetobutylicum. | many bacteria, in particular gram-positives, contain high proportions of non-n-acetylated amino sugars, i.e. glucosamine (glcn) and/or muramic acid (murn), in the peptidoglycan of their cell wall, thereby acquiring resistance to lysozyme. however, muramidases with specificity for non-n-acetylated peptidoglycan have been characterized as part of autolytic systems such as of clostridium acetobutylicum. we aim to elucidate the recovery pathway for non-n-acetylated peptidoglycan fragments and presen ... | 2011 | 21784938 |
| σk of clostridium acetobutylicum is the first known sporulation-specific sigma factor with two developmentally separated roles, one early and one late in sporulation. | sporulation in the model endospore-forming organism bacillus subtilis proceeds via the sequential and stage-specific activation of the sporulation-specific sigma factors, σ(h) (early), σ(f), σ(e), σ(g), and σ(k) (late). here we show that the clostridium acetobutylicum σ(k) acts both early, prior to spo0a expression, and late, past σ(g) activation, thus departing from the b. subtilis model. the c. acetobutylicum sigk deletion (δsigk) mutant was unable to sporulate, and solventogenesis, the charac ... | 2014 | 24187083 |
| characterisation of an n-acetylmuramic acid/n-acetylglucosamine kinase of clostridium acetobutylicum. | here, we report the cloning and characterisation of a cytoplasmic kinase of clostridium acetobutylicum, named murk (for murein sugar kinase). the enzyme has a unique specificity for both amino sugars of the bacterial cell wall, n-acetylmuramic acid (murnac) and n-acetylglucosamine (glcnac), which are phosphorylated at the 6-hydroxyl group. kinetic analyses revealed k(m)values of 190 and 127 µm for murnac and glcnac, respectively, and a k(cat) value (65.0 sec(-1)) that was 1.5 fold higher for the ... | 2011 | 21784936 |
| light-driven biocatalysis with cytochrome p450 peroxygenases. | the cytochrome p450 peroxygenases p450(bsβ) (cyp152a1) from bacillus subtilis and p450(cla) (cyp152a2) from clostridium acetobutylicum belong to a unique group of p450s with high synthetic potential. they consume hydrogen peroxide via the peroxide shunt and therefore do not require additional electron transfer proteins for biocatalytic activity. their high synthetic potential is, however, impaired by their rather poor operational stability in the presence of hydrogen peroxide. herein, we report ... | 2013 | 23586998 |
| resolving cell composition through simple measurements, genome-scale modeling, and a genetic algorithm. | the biochemical composition of a cell is very complex and dynamic. it varies greatly among different organisms and environmental conditions. inclusion of proper cell composition data is critical for accurate genome-scale metabolic flux modeling using flux balance analysis (fba). however, determining cell composition experimentally is currently time-consuming and resource intensive. in this chapter, a method for predicting cell composition using a genome-scale model and "easy to measure" culture ... | 2013 | 23417800 |
| a modified pathway for the production of acetone in escherichia coli. | a modified synthetic acetone operon was constructed. it consists of two genes from clostridium acetobutylicum (thla coding for thiolase and adc coding for acetoacetate decarboxylase) and one from bacillus subtilis or haemophilus influenzae (teii(srf) or ybgc, respectively, for thioesterase). expression of this operon in escherichia coli resulted in the production of acetone starting from the common metabolite acetyl-coa via acetoacetyl-coa and acetoacetate. the thioesterases do not need a coa ac ... | 2013 | 22906955 |
| spoiie is necessary for asymmetric division, sporulation, and the expression of {sigma}f, {sigma}e, and {sigma}g, but does not control solvent production in clostridium acetobutylicum. | in order to better characterize the initial stages of sporulation past spo0a activation and the associated solventogenesis in the important industrial and model organism clostridium acetobutylicum, the spoiie gene was successfully disrupted and its expression silenced. by silencing spoiie, sporulation was blocked prior to asymmetric division, and no mature spores or any distinguishable morphogenetic changes developed. upon plasmid-based complementation of spoiie, sporulation was restored, althou ... | 2011 | 21784928 |
| a synthetic o2 -tolerant butanol pathway exploiting native fatty acid biosynthesis in escherichia coli. | several synthetic metabolic pathways for butanol synthesis have been reported in escherichia coli by modification of the native coa-dependent pathway from selected clostridium species. these pathways are all dependent on the o2 -sensitive adhe2 enzyme from clostridium acetobutylicum that catalyzes the sequential reduction of both butyryl-coa and butyraldehyde. we constructed an o2 -tolerant butanol pathway based on the activities of an acp-thioesterase, acting on butyryl-acp in the native fatty ... | 2015 | 24981220 |
| measurement of biochemical oxygen demand from different wastewater samples using a mediator-less microbial fuel cell biosensor. | microbial fuel cells (mfcs) have attracted considerable attention as potential biosensors. a mfc biosensor for rapid measurement of biochemical oxygen demand (bod) has been recently studied. however, a standardized bacterial mixture inoculated in the mfc biosensor for bod measurement is unavailable. thus, the commercial application of a mfc biosensor is limited. in this study, a mediator-less mfc biosensor inoculated with known mixed cultures to quickly determine bod concentration was tested. op ... | 2014 | 25145173 |
| a roadmap for gene system development in clostridium. | clostridium species are both heroes and villains. some cause serious human and animal diseases, those present in the gut microbiota generally contribute to health and wellbeing, while others represent useful industrial chassis for the production of chemicals and fuels. to understand, counter or exploit, there is a fundamental requirement for effective systems that may be used for directed or random genome modifications. we have formulated a simple roadmap whereby the necessary gene systems maybe ... | 2016 | 27234263 |
| an improved kinetic model for the acetone-butanol-ethanol pathway of clostridium acetobutylicum and model-based perturbation analysis. | comprehensive kinetic models of microbial metabolism can enhance the understanding of system dynamics and regulatory mechanisms, which is helpful in optimizing microbial production of industrial chemicals. clostridium acetobutylicum produces solvents (acetone-butanol-ethanol, abe) through the abe pathway. to systematically assess the potential of increased production of solvents, kinetic modeling has been applied to analyze the dynamics of this pathway and make predictive simulations. up to date ... | 2011 | 21689471 |
| small rnas in the genus clostridium. | the genus clostridium includes major human pathogens and species important to cellulose degradation, the carbon cycle, and biotechnology. small rnas (srnas) are emerging as crucial regulatory molecules in all organisms, but they have not been investigated in clostridia. research on srnas in clostridia is hindered by the absence of a systematic method to identify srna candidates, thus delegating clostridial srna research to a hit-and-miss process. thus, we wanted to develop a method to identify p ... | 2011 | 21264064 |
| resolving the tca cycle and pentose-phosphate pathway of clostridium acetobutylicum atcc 824: isotopomer analysis, in vitro activities and expression analysis. | solventogenic clostridia are an important class of microorganisms that can produce various biofuels. one of the bottlenecks in engineering clostridia stems from the fact that central metabolic pathways remain poorly understood. here, we utilized the power of (13) c-based isotopomer analysis to re-examine central metabolic pathways of clostridium acetobutylicum atcc 824. we demonstrate using [1,2-(13) c]glucose, ms analysis of intracellular metabolites, and enzymatic assays that c. acetobutylicum ... | 2010 | 21370473 |
| genomic sequence of bacteriophage atcc 8074-b1 and activity of its endolysin and engineered variants against clostridium sporogenes. | lytic bacteriophage atcc 8074-b1 produces large plaques on its host clostridium sporogenes. sequencing of the 47,595-bp genome allowed the identification of 82 putative open reading frames, including those encoding proteins for head and tail morphogenesis and lysis. however, sequences commonly associated with lysogeny were absent. orf 22 encodes an endolysin, cs74l, that shows homology to n-acetylmuramoyl-l-alanine amidases, and when expressed in escherichia coli, the protein causes effective ly ... | 2012 | 22427494 |
| lipid diversity among botulinum neurotoxin-producing clostridia. | clostridium botulinum has been classified into four groupings (groups i to iv) based on physiological characteristics and 16s rrna sequencing. we have examined the lipid compositions of 11 representative strains of c. botulinum and a strain of clostridium sporogenes by 2d-tlc and by ms. all strains contained phosphatidylglycerol (pg), cardiolipin (cl) and phosphatidylethanolamine (pe) in both the all-acyl and the alk-1'-enyl (plasmalogen) forms. five strains in proteolytic group i, which are rel ... | 2012 | 22837302 |
| comparative shotgun proteomic analysis of clostridium acetobutylicum from butanol fermentation using glucose and xylose. | abstract: | 2011 | 22008648 |
| disruption of the acetate kinase (ack) gene of clostridium acetobutylicum results in delayed acetate production. | in microorganisms, the enzyme acetate kinase (ak) catalyses the formation of atp from adp by de-phosphorylation of acetyl phosphate into acetic acid. a mutant strain of clostridium acetobutylicum lacking acetate kinase activity is expected to have reduced acetate and acetone production compared to the wild type. in this work, a c. acetobutylicum mutant strain with a selectively disrupted ack gene, encoding ak, was constructed and genetically and physiologically characterized. the ack ... | 2012 | 22249720 |
| a functional rect gene for recombineering of clostridium. | recombineering is an efficient genetic manipulation method employing the mechanism of phagenic rect-mediated homologous recombination. to develop a recombineering method for clostridium, a putative rect gene (cpf0939) from clostridium perfringens genome was functionally verified in a clostridial host clostridium acetobutylicum. we show that a short synthetic oligonucleotide can be introduced into the target site for specific point mutation. this functional rect gene would therefore contribute to ... | 2014 | 24384234 |
| novel system for efficient isolation of clostridium double-crossover allelic exchange mutants enabling markerless chromosomal gene deletions and dna integration. | isolation of clostridium mutants based on gene replacement via allelic exchange remains a major limitation for this important genus. use of a heterologous counterselection marker can facilitate the identification of the generally rare allelic exchange events. we report on the development of an inducible counterselection marker and describe its utility and broad potential in quickly and efficiently generating markerless dna deletions and integrations at any genomic locus without the need for auxo ... | 2012 | 22983967 |
| in situ hydrogen, acetone, butanol, ethanol and microdiesel production by clostridium acetobutylicum atcc 824 from oleaginous fungal biomass. | an in situ batch fermentation technique was employed for biohydrogen, acetone, butanol, ethanol and microdiesel production from oleaginous fungal biomass using the anaerobic fermentative bacterium clostridium acetobutylicum atcc 824. oleaginous fungal cunninghamella echinulata biomass which has ability to accumulate up to 71% cellular lipid was used as the substrate carbon source. the maximum cumulative hydrogen by c. acetobutylicum atcc 824 from crude c. echinulata biomass was 260 ml h2 l(-1), ... | 2015 | 26014369 |
| crystal structure of clostridium acetobutylicum aspartate kinase (caak): an important allosteric enzyme for amino acids production. | aspartate kinase (ak) is an enzyme which is tightly regulated through feedback control and responsible for the synthesis of 4-phospho-l-aspartate from l-aspartate. this intermediate step is at an important branch point where one path leads to the synthesis of lysine and the other to threonine, methionine and isoleucine. concerted feedback inhibition of ak is mediated by threonine and lysine and varies between the species. the crystal structure of biotechnologically important clostridium acetobut ... | 2014 | 25170437 |
| inhibition of biocatalysis in [fe-fe] hydrogenase by oxygen: molecular dynamics and density functional theory calculations. | designing o(2)-tolerant hydrogenases is a major challenge in applying [fe-fe]h(2)ases for h(2) production. the inhibition involves transport of oxygen through the enzyme to the h-cluster, followed by binding and subsequent deactivation of the active site. to explore the nature of the oxygen diffusion channel for the hydrogenases from desulfovibrio desulfuricans (dd) and clostridium pasteurianum (cp), empirical molecular dynamics simulations were performed. the dynamic nature of the oxygen pathwa ... | 2012 | 22563793 |
| genetic modifications and introduction of heterologous pdc genes in enterococcus faecalis for its use in production of bioethanol. | genetically-modified enterococcus faecalis has a potential of survival and can be used in ethanolic fermentations. fermentation profiles of e. faecalis jh2-2 were assessed using glucose and lactose as carbon sources. deletion of lactate dehydrogenase (ldh) genes increased the ethanol production from 0.25 to 0.82 g/l, which was further increased to 0.96 g/l by the insertion of a pyruvate decarboxylase (pdc) gene (from sarcina ventriculi or clostridium acetobutylicum) in place ldh1. when grown on ... | 2012 | 22628022 |
| screened butanol-tolerant enterococcus faecium capable of butanol production. | due to the complex mechanisms involved in butanol-induced stress response, butanol tolerance phenotype is difficult to engineer even in microorganisms with well-defined genetic backgrounds. we therefore aimed to isolate butanol-tolerant microorganisms from environmental samples as potential alternative hosts for butanol production. soil samples collected were subjected to butanol stress. a microbial strain capable of 2.5-3 % (w/v) butanol tolerance was isolated and identified as enterococcus fae ... | 2012 | 22961352 |
| expression and characterization of levansucrase from clostridium acetobutylicum. | the clostridium acetobutylicum gene ca-sacb encoding levansucrase was cloned and expressed in escherichia coli. ca-sacb is composed of 1287 bp and encodes 428 amino acid residues, which could convert 150 mmol/l sucrose to levan with the liberation of glucose. the optimum ph and temperature of this enzyme for levan formation were ph 6 and 60 °c, respectively. levansucrase activity of ca-sacb was completely abolished by 5 mmol/l ag(+) and hg(2+). the km and vmax values for levansucrase were calcul ... | 2017 | 28075130 |
| retargeting a dual-acting srna for multiple mrna transcript regulation. | multitargeting small regulatory rnas (srnas) represent a potentially useful tool for metabolic engineering applications. natural multitargeting srnas govern bacterial gene expression by binding to the translation initiation regions of protein-coding mrnas through base pairing. we designed an escherichia coli based genetic system to create and assay dual-acting retargeted-srna variants. the variants can be assayed for coordinate translational regulation of two alternate mrna leaders fused to inde ... | 2017 | 28067500 |
| efficient gene knockdown in clostridium acetobutylicum by synthetic small regulatory rnas. | clostridium is considered a promising microbial host for the production of valuable industrial chemicals. however, clostridium is notorious for the difficulty of genetic manipulations, and consequently metabolic engineering. thus, much effort has been exerted to develop novel tools for genetic and metabolic engineering of clostridium strains. here, we report the development of a synthetic small regulatory rna (srna)-based system for controlled gene expression in clostridium acetobutylicum, consi ... | 2017 | 27531464 |
| thermochemical hydrolysis of macroalgae ulva for biorefinery: taguchi robust design method. | understanding the impact of all process parameters on the efficiency of biomass hydrolysis and on the final yield of products is critical to biorefinery design. using taguchi orthogonal arrays experimental design and partial least square regression, we investigated the impact of change and the comparative significance of thermochemical process temperature, treatment time, %acid and %solid load on carbohydrates release from green macroalgae from ulva genus, a promising biorefinery feedstock. the ... | 2016 | 27291594 |
| application to photocatalytic h2 production of a whole-cell reaction by recombinant escherichia coli cells expressing [fefe]-hydrogenase and maturases genes. | a photocatalytic h2 production system using an inorganic-bio hybrid photocatalyst could contribute to the efficient utilization of solar energy, but would require the development of a new approach for preparing a h2 -forming biocatalyst. in the present study, we constructed a recombinant strain of escherichia coli expressing the genes encoding the [fefe]-hydrogenase and relevant maturases from clostridium acetobutylicum nbrc 13948 for use as a biocatalyst. we investigated the direct application ... | 2016 | 27194524 |
| co-production of acetone and ethanol with molar ratio control enables production of improved gasoline or jet fuel blends. | the fermentation of simple sugars to ethanol has been the most successful biofuel process to displace fossil fuel consumption worldwide thus far. however, the physical properties of ethanol and automotive components limit its application in most cases to 10-15 vol% blends with conventional gasoline. fermentative co-production of ethanol and acetone coupled with a catalytic alkylation reaction could enable the production of gasoline blendstocks enriched in higher-chain oxygenates. here we demonst ... | 2016 | 26987294 |
| raman spectroscopy detects phenotypic differences among escherichia coli enriched for 1-butanol tolerance using a metagenomic dna library. | advances in raman spectroscopy are enabling more comprehensive measurement of microbial cell chemical composition. advantages include results returned in near real-time and minimal sample preparation. in this research, raman spectroscopy is used to analyze e. coli with engineered solvent tolerance, which is a multi-genic trait associated with complex and uncharacterized phenotypes that are of value to industrial microbiology. to generate solvent tolerant phenotypes, e. coli transformed with dna ... | 2016 | 26814030 |
| feasibility of installing and maintaining anaerobiosis using escherichia coli hd701 as a facultative anaerobe for hydrogen production by clostridium acetobutylicum atcc 824 from various carbohydrates. | using escherichia coli for installing and maintaining anaerobiosis for hydrogen production by clostridium acetobutylicum atcc 824 is a cost-effective approach for industrial hydrogen production, as it does not require reducing agents or sparging with inert gases. this study was devoted for investigating the feasibility for installing and maintaining anaerobiosis of hydrogen production by c. acetobutylicum atcc 824 when using e. coli hd701 utilizable versus non utilizable sugars as a-carbon sourc ... | 2015 | 26453472 |
| small acid-soluble spore proteins of clostridium acetobutylicum are able to protect dna in vitro and are specifically cleaved by germination protease gpr and spore protease yyac. | small acid-soluble proteins (sasps) play an important role in protection of dna in dormant bacterial endospores against damage by heat, uv radiation or enzymic degradation. in the genome of the strict anaerobe clostridium acetobutylicum, five genes encoding sasps have been annotated and here a further sixth candidate is suggested. the ssp genes are expressed in parallel dependent upon spo0a, a master regulator of sporulation. analysis of the transcription start points revealed a σg or a σf conse ... | 2015 | 26362088 |
| characterization of an acetoin reductase/2,3-butanediol dehydrogenase from clostridium ljungdahlii dsm 13528. | acetoin reductase catalyzes the formation of 2,3-butanediol from acetoin. in clostridium ljungdahlii dsm 13528, the gene clju_c23220 encoding the putative zn(2+)-dependent alcohol dehydrogenase was cloned and expressed in escherichia coli. the recombinant enzyme, clar, can catalyze the conversion of acetoin to 2,3-butanediol with nadph as the cofactor. furthermore, the gene clju_c23220 was introduced into clostridium acetobutylicum atcc 824 and the transformant was conferred the capacity of 2,3- ... | 2015 | 26320708 |
| a new shuttle plasmid that stably replicates in clostridium acetobutylicum. | we have developed a new shuttle plasmid, designated as plk1-mcs that can replicate in both clostridium acetobutylicum and escherichia coli, by combining the pub110 and puc19 plasmids. plasmid plk1-mcs replicated more stably than previously reported plasmids containing either the pim13 or the pamβ1 replicon in the absence of antibiotic selective pressure. the transfer frequency of plk1-mcs into c. acetobutylicum was similar to the transfer frequency of other shuttle plasmids. we complemented c. a ... | 2015 | 26032368 |
| improved n-butanol tolerance in escherichia coli by controlling membrane related functions. | as the increasing demand from both chemical and fuel markets, the interest in producing n-butanol using biological route has been rejuvenated to engineer an economical fermentation process, competing with the currently-dominant chemical synthesis. n-butanol has been traditionally produced from the abe fermentation of clostridium acetobutylicum. this system, however, is not economically feasible due to its limited efficiency and the lack of genetic modification tools for further improvements. alt ... | 2015 | 25858152 |
| comparative transcriptome analysis between csra-disruption clostridium acetobutylicum and its parent strain. | the genome of clostridium acetobutylicum contains the gene encoding csra, a carbon storage regulator. we investigated the function of csra in c. acetobutylicum by insertionally inactivating the encoding gene, ca_c2209 using the clostron. disruption of csra obviously decreases the growth of the organism and reduces the yield of acetone, butanol and ethanol (abes). like the csra in escherichia coli, rna-seq and β-galactosidase analysis revealed that csra in c. acetobutylicum was closely involved i ... | 2015 | 25832359 |
| genetic improvement of n-butanol tolerance in escherichia coli by heterologous overexpression of groesl operon from clostridium acetobutylicum. | strain tolerance to toxic metabolites remains an important issue in the production of biofuels. here we examined the impact of overexpressing the heterologous groesl chaperone from clostridium acetobutylicum to enhance the tolerance of escherichia coli against several stressors. strain tolerance was identified using strain maximum specific growth rate (μ) and strain growth after a period of solvent exposure. in comparison with control strain, the groesl overexpressing strain yielded a 27 % incre ... | 2015 | 28324542 |
| engineering cellular robustness of microbes by introducing the groesl chaperonins from extremophilic bacteria. | the cellular robustness is a big concern for efficient microbial production of biofuels and biochemicals. in this study, the groesl genes from extremophilic bacteria were found to serve as transplantable stress-response elements to improve diverse types of stress-tolerances of other microbes. by overexpressing the groesl from the solvent-tolerant pseudomonas putida in escherichia coli, its thermo-tolerance and ethanol-tolerance were significantly increased. meanwhile, the groesl from the thermop ... | 2014 | 24637367 |
| microbial production of short-chain alkanes. | increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. here we report the development of platform escherichia coli strains that are capable of producing short-chain alkanes (scas; petrol), free fatty acids (ffas), fatty ... | 2013 | 24077097 |
| engineering a synthetic pathway in cyanobacteria for isopropanol production directly from carbon dioxide and light. | production of alternate fuels or chemicals directly from solar energy and carbon dioxide using engineered cyanobacteria is an attractive method to reduce petroleum dependency and minimize carbon emissions. here, we constructed a synthetic pathway composed of acetyl-coa acetyl transferase (encoded by thl), acetoacetyl-coa transferase (encoded by atoad), acetoacetate decarboxylase (encoded by adc) and secondary alcohol dehydrogenase (encoded by adh) in synechococcus elongatus strain pcc 7942 to pr ... | 2013 | 24076145 |
| engineering e. coli strain for conversion of short chain fatty acids to bioalcohols. | recent progress in production of various biofuel precursors and molecules, such as fatty acids, alcohols and alka(e)nes, is a significant step forward for replacing the fossil fuels with renewable fuels. a two-step process, where fatty acids from sugars are produced in the first step and then converted to corresponding biofuel molecules in the second step, seems more viable and attractive at this stage. we have engineered an escherichia coli strain to take care of the second step for converting ... | 2013 | 24020887 |
| conversion of levulinic acid to 2-butanone by acetoacetate decarboxylase from clostridium acetobutylicum. | in this study, a novel system for synthesis of 2-butanone from levulinic acid (γ-keto-acid) via an enzymatic reaction was developed. acetoacetate decarboxylase (aadc; e.c. 4.1.1.4) from clostridium acetobutylicum was selected as a biocatalyst for decarboxylation of levulinic acid. the purified recombinant aadc from escherichia coli successfully converted levulinic acid to 2-butanone with a conversion yield of 8.4-90.3 % depending on the amount of aadc under optimum conditions (30 °c and ph 5.0) ... | 2013 | 23624707 |
| butyrate production in engineered escherichia coli with synthetic scaffolds. | butyrate pathway was constructed in recombinant escherichia coli using the genes from clostridium acetobutylicum and treponema denticola. however, the pathway constructed from exogenous enzymes did not efficiently convert carbon flux to butyrate. three steps of the productivity enhancement were attempted in this study. first, pathway engineering to delete metabolic pathways to by-products successfully improved the butyrate production. second, synthetic scaffold protein that spatially co-localize ... | 2013 | 23568786 |
| deriving metabolic engineering strategies from genome-scale modeling with flux ratio constraints. | optimized production of bio-based fuels and chemicals from microbial cell factories is a central goal of systems metabolic engineering. to achieve this goal, a new computational method of using flux balance analysis with flux ratios (fbratio) was further developed in this research and applied to five case studies to evaluate and design metabolic engineering strategies. the approach was implemented using publicly available genome-scale metabolic flux models. synthetic pathways were added to these ... | 2013 | 23460591 |
| engineering of nadph regenerators in escherichia coli for enhanced biotransformation. | efficient regeneration of nadph is one of the limiting factors that constrain the productivity of biotransformation processes. in order to increase the availability of nadph for enhanced biotransformation by engineered escherichia coli, modulation of the pentose phosphate pathway and amplification of the transhydrogenases system have been conventionally attempted as primary solutions. recently, other approaches for stimulating nadph regeneration during glycolysis, such as replacement of native g ... | 2013 | 23420268 |
| pyruvate:ferredoxin oxidoreductase is coupled to light-independent hydrogen production in chlamydomonas reinhardtii. | in anaerobiosis, the green alga chlamydomonas reinhardtii evolves molecular hydrogen (h(2)) as one of several fermentation products. h(2) is generated mostly by the [fe-fe]-hydrogenase hyda1, which uses plant type ferredoxin petf/fdx1 (petf) as an electron donor. dark fermentation of the alga is mainly of the mixed acid type, because formate, ethanol, and acetate are generated by a pyruvate:formate lyase pathway similar to escherichia coli. however, c. reinhardtii also possesses the pyruvate:fer ... | 2013 | 23258532 |
| thiolase engineering for enhanced butanol production in clostridium acetobutylicum. | biosynthetic thiolases catalyze the condensation of two molecules acetyl-coa to acetoacetyl-coa and represent key enzymes for carbon-carbon bond forming metabolic pathways. an important biotechnological example of such a pathway is the clostridial n-butanol production, comprising various natural constraints that limit titer, yield, and productivity. in this study, the thiolase of clostridium acetobutylicum, the model organism for solventogenic clostridia, was specifically engineered for reduced ... | 2013 | 23096577 |
| a selection platform for carbon chain elongation using the coa-dependent pathway to produce linear higher alcohols. | production of green chemicals and fuels using metabolically engineered organisms has been a promising alternative to petroleum-based production. higher chain alcohols (c4-c8) are of interest because they can be used as chemical feedstock as well as fuels. recently, the feasibility of n-hexanol synthesis using escherichia coli has been demonstrated by extending the modified clostridium coa-dependent n-butanol synthesis pathway, thereby elongating carbon chain length via reactions in reversed β-ox ... | 2012 | 22819734 |
| [cloning and expression of key genes of butanol synthetic pathway in escherichia coli]. | we constructed a recombinant escherichia coli strain for butanol production by cloning the cdna sequence of the key butanol synthetic pathway genes from clostridium acetobutylicum atcc824. | 2012 | 22803344 |
| engineering a homobutanol fermentation pathway in escherichia coli eg03. | a homobutanol fermentation pathway was engineered in a derivative of escherichia coli b (glucose [glycolysis] => 2 pyruvate + 2 nadh; pyruvate [pyruvate dehydrogenase] => acetyl-coa + nadh; 2 acetyl-coa [butanol pathway enzymes] + 4 nadh => butanol; summary stoichiometry: glucose => butanol). initially, the native fermentation pathways were eliminated from e. coli b by deleting the genes encoding for lactate dehydrogenase (ldha), acetate kinase (acka), fumarate reductase (frdabcd), pyruvate form ... | 2012 | 22776992 |
| integration of dna into bacterial chromosomes from plasmids without a counter-selection marker. | most bacteria can only be transformed with circular plasmids, so robust dna integration methods for these rely upon selection of single-crossover clones followed by counter-selection of double-crossover clones. to overcome the limited availability of heterologous counter-selection markers, here we explore novel dna integration strategies that do not employ them, and instead exploit (i) activation or inactivation of genes leading to a selectable phenotype, and (ii) asymmetrical regions of homolog ... | 2012 | 22259038 |
| proliferation of diversified clostridial species during biological soil disinfestation incorporated with plant biomass under various conditions. | biological soil disinfestation (bsd) involves the anaerobic decomposition of plant biomass by microbial communities leading to control of plant pathogens. we analyzed bacterial communities in soil of a model experiment of bsd, as affected by biomass incorporation under various conditions, to find out the major anaerobic bacterial groups which emerged after bsd treatments. the soil was treated with brassica juncea plants, wheat bran, or avena strigosa plants, irrigated at 20 or 30 % moisture cont ... | 2013 | 23132344 |
| a novel arabinose-inducible genetic operation system developed for clostridium cellulolyticum. | clostridium cellulolyticum and other cellulolytic clostridium strains are natural producers of lignocellulosic biofuels and chemicals via the consolidated bioprocessing (cbp) route, and systems metabolic engineering is indispensable to meet the cost-efficient demands of industry. several genetic tools have been developed for clostridium strains, and an efficient and stringent inducible genetic operation system is still required for the precise regulation of the target gene function. | 2015 | 25763107 |
| enhanced butanol production obtained by reinforcing the direct butanol-forming route in clostridium acetobutylicum. | butanol is an important industrial solvent and advanced biofuel that can be produced by biphasic fermentation by clostridium acetobutylicum. it has been known that acetate and butyrate first formed during the acidogenic phase are reassimilated to form acetone-butanol-ethanol (cold channel). butanol can also be formed directly from acetyl-coenzyme a (coa) through butyryl-coa (hot channel). however, little is known about the relative contributions of the two butanol-forming pathways. here we repor ... | 2012 | 23093384 |
| metabolic engineering of an atp-neutral embden-meyerhof-parnas pathway in corynebacterium glutamicum: growth restoration by an adaptive point mutation in nadh dehydrogenase. | corynebacterium glutamicum uses the embden-meyerhof-parnas pathway of glycolysis and gains 2 mol of atp per mol of glucose by substrate-level phosphorylation (slp). to engineer glycolysis without net atp formation by slp, endogenous phosphorylating nad-dependent glyceraldehyde-3-phosphate dehydrogenase (gapdh) was replaced by nonphosphorylating nadp-dependent glyceraldehyde-3-phosphate dehydrogenase (gapn) from clostridium acetobutylicum, which irreversibly converts glyceraldehyde-3-phosphate (g ... | 2015 | 25576602 |
| fermentation of oxidized hexose derivatives by clostridium acetobutylicum. | clostridium acetobutylicum fermentations are promising for production of commodity chemicals from heterogeneous biomass due to the wide range of substrates the organism can metabolize. much work has been done to elucidate the pathways for utilization of aldoses, but little is known about metabolism of more oxidized substrates. two oxidized hexose derivatives, gluconate and galacturonate, are present in low cost feedstocks, and their metabolism will contribute to overall metabolic output of these ... | 2014 | 25231163 |
| Metabolic Engineering of Clostridium acetobutylicum ATCC 824 for Isopropanol-Butanol-Ethanol Fermentation. | Clostridium acetobutylicum naturally produces acetone as well as butanol and ethanol. Since acetone cannot be used as a biofuel, its production needs to be minimized or suppressed by cell or bioreactor engineering. Thus, there have been attempts to disrupt or inactivate the acetone formation pathway. Here we present another approach, namely converting acetone to isopropanol by metabolic engineering. Since isopropanol can be used as a fuel additive, the mixture of isopropanol, butanol, and ethano ... | 2011 | 22210214 |
| development of an anhydrotetracycline-inducible gene expression system for solvent-producing clostridium acetobutylicum: a useful tool for strain engineering. | clostridium acetobutylicum is an important solvent (acetone-butanol-ethanol) producing bacterium. however, a stringent, effective, and convenient-to-use inducible gene expression system that can be used for regulating the gene expression strength in c. acetobutylicum is currently not available. here, we report an anhydrotetracycline-inducible gene expression system for solvent-producing bacterium c. acetobutylicum. this system consists of a functional chloramphenicol acetyltransferase gene promo ... | 2011 | 22056607 |
| confirmation and elimination of xylose metabolism bottlenecks in glucose phosphoenolpyruvate-dependent phosphotransferase system-deficient clostridium acetobutylicum for simultaneous utilization of glucose, xylose, and arabinose. | efficient cofermentation of d-glucose, d-xylose, and l-arabinose, three major sugars present in lignocellulose, is a fundamental requirement for cost-effective utilization of lignocellulosic biomass. the gram-positive anaerobic bacterium clostridium acetobutylicum, known for its excellent capability of producing abe (acetone, butanol, and ethanol) solvent, is limited in using lignocellulose because of inefficient pentose consumption when fermenting sugar mixtures. to overcome this substrate util ... | 2011 | 21926197 |
| biobutanol. | china initiated its acetone-butanol-ethanol (abe) industry in the 1950s; it peaked in the 1980s, and ended at the end of the last century owing to the development of more competitive petrochemical pathways. however, driven by the high price of crude oil and environmental concerns raised by the over-consumption of petrochemical products, biofuels and bio-based chemicals including butanol have garnered global attention again. currently, butanol produced from abe fermentation is mainly used as an i ... | 2011 | 22167047 |
| Ribulokinase and Transcriptional Regulation of Arabinose Metabolism in Clostridium acetobutylicum. | The transcription factor AraR controls utilization of l-arabinose in Bacillus subtilis. In this study we combined a comparative genomic reconstruction of AraR regulons in nine Clostridium species with the detailed experimental characterization of AraR-mediated regulation in Clostridium acetobutylicum. Based on the reconstructed AraR regulons, a novel ribulokinase AraK present in all analyzed Clostridium species was identified, which was a non-orthologous replacement of previously characterized r ... | 2011 | 22194461 |
| Controlling the oxidoreduction potential of the culture of Clostridium acetobutylicum leads to an earlier initiation of solventogenesis, thus increasing solvent productivity. | Fermentative production of solvents (acetone, butanol, and ethanol) by Clostridium acetobutylicum is generally a biphasic process consisting of acidogenesis and solventogenesis. We report that the biphasic metabolism of C. acetobutylicum could be changed by oxidoreduction potential (ORP) regulation. When using air to control the ORP of the fermentation broth at -290 mV, an earlier initiation of solventogenesis was achieved. Solvent production reached 25.6 g?l(-1) (2.8 g acetone l(-1), 16.8 g but ... | 2011 | 21935591 |
| An agr quorum sensing system regulates granulose formation and sporulation in Clostridium acetobutylicum. | The Gram-positive, anaerobic, endospore-forming bacterium Clostridium acetobutylicum has considerable biotechnological potential due to its ability to produce solvents as fermentation products, in particular the biofuel butanol. Its genome contains a putative agr locus, agrBDCA, known in staphylococci to constitute a cyclic peptide-based quorum sensing system. In staphylococci, agrBD is required for the generation of a peptide signal that, upon extracellular accumulation, is sensed by an agrCA-e ... | 2011 | 22179241 |
| structural analysis of clostridium acetobutylicum atcc 824 glycoside hydrolase from cazy family gh105. | clostridium acetobutylicum atcc 824 gene ca_c0359 encodes a putative unsaturated rhamnogalacturonyl hydrolase (urh) with distant amino-acid sequence homology to yter of bacillus subtilis strain 168. yter, like other urhs, has core structural homology to unsaturated glucuronyl hydrolases, but hydrolyzes the unsaturated disaccharide derivative of rhamnogalacturonan i. the crystal structure of the recombinant ca_c0359 protein was solved to 1.6 å resolution by molecular replacement using the phase i ... | 2015 | 26249707 |
| isolation and characterisation of non-anaerobic butanol-producing symbiotic system tsh06. | butanol-producing microorganisms are all obligate anaerobes. in this study, a unique symbiotic system tsh06 was isolated to be capable of producing butanol under non-anaerobic condition. denaturing gradient gel electrophoresis (dgge) analysis of 16s ribosomal rna (rrna) revealed that two strains coexist in tsh06. the two strains were identical to clostridium acetobutylicum and bacillus cereus, respectively. they were isolated individually and named as c. acetobutylicum tsh1 and b. cereus tsh2. c ... | 2015 | 26272091 |
| enhanced production of butanol and acetoin by heterologous expression of an acetolactate decarboxylase in clostridium acetobutylicum. | butanol is an important industrial chemical and an attractive transportation fuel. however, the deficiency of reducing equivalents nad(p)h in butanol fermentation results in a large quantity of oxidation products, which is a major problem limiting the atom economy and economic viability of bio-butanol processes. here, we integrated the butanol fermentation process with a nadh-generating, acetoin biosynthesis process to improve the butanol production. by overexpressing the α-acetolactate decarbox ... | 2016 | 27285575 |
| non-conserved residues in clostridium acetobutylicum trna(ala) contribute to trna tuning for efficient antitermination of the alas t box riboswitch. | the t box riboswitch regulates expression of amino acid-related genes in gram-positive bacteria by monitoring the aminoacylation status of a specific trna, the binding of which affects the folding of the riboswitch into mutually exclusive terminator or antiterminator structures. two main pairing interactions between the trna and the leader rna have been demonstrated to be necessary, but not sufficient, for efficient antitermination. in this study, we used the clostridium acetobutylicum alas gene ... | 2015 | 26426057 |
| the clostridium sporulation programs: diversity and preservation of endospore differentiation. | bacillus and clostridium organisms initiate the sporulation process when unfavorable conditions are detected. the sporulation process is a carefully orchestrated cascade of events at both the transcriptional and posttranslational levels involving a multitude of sigma factors, transcription factors, proteases, and phosphatases. like bacillus genomes, sequenced clostridium genomes contain genes for all major sporulation-specific transcription and sigma factors (spo0a, sigh, sigf, sige, sigg, and s ... | 2015 | 25631287 |
| metabolic engineering of corynebacterium glutamicum for increasing the production of l-ornithine by increasing nadph availability. | the experiments presented here were based on the conclusions of our previous proteomic analysis. increasing the availability of glutamate by overexpression of the genes encoding enzymes in the l-ornithine biosynthesis pathway upstream of glutamate and disruption of spee, which encodes spermidine synthase, improved l-ornithine production by corynebacterium glutamicum. production of l-ornithine requires 2 moles of nadph per mole of l-ornithine. thus, the effect of nadph availability on l-ornithine ... | 2013 | 23836141 |
| a role for his-160 in peroxide inhibition of s. cerevisiae s-formylglutathione hydrolase: evidence for an oxidation sensitive motif. | while the general catalytic mechanism of the widespread serine hydrolase superfamily has been documented extensively, much less is known about its varied modes of functional modulation within biological systems. under oxidizing conditions, inhibition of saccharomyces cerevisiae s-formylglutathione hydrolase (sfgh, homologous to human esterase d) activity is attributable to a cysteine (cys-60) adjacent to its catalytic triad and approximately 8.0 å away from the oγ of the nucleophilic serine. cys ... | 2012 | 22906720 |
| mutant generation by allelic exchange and genome resequencing of the biobutanol organism clostridium acetobutylicum atcc 824. | clostridium acetobutylicum represents a paradigm chassis for the industrial production of the biofuel biobutanol and a focus for metabolic engineering. we have previously developed procedures for the creation of in-frame, marker-less deletion mutants in the pathogen clostridium difficile based on the use of pyre and coda genes as counter selection markers. in the current study we sought to test their suitability for use in c. acetobutylicum. | 2016 | 26732067 |
| a universal mariner transposon system for forward genetic studies in the genus clostridium. | dna transposons represent an essential tool in the armoury of the molecular microbiologist. we previously developed a catp-based mini transposon system for clostridium difficile in which the expression of the transposase gene was dependent on a sigma factor unique to c. difficile, tcdr. here we have shown that the host range of the transposon is easily extended through the rapid chromosomal insertion of the tcdr gene at the pyre locus of the intended clostridial target using allele-coupled excha ... | 2015 | 25836262 |
| automated 3d rna structure prediction using the rnacomposer method for riboswitches. | understanding the numerous functions of rnas depends critically on the knowledge of their three-dimensional (3d) structure. in contrast to the protein field, a much smaller number of rna 3d structures have been assessed using x-ray crystallography, nmr spectroscopy, and cryomicroscopy. this has led to a great demand to obtain the rna 3d structures using prediction methods. the 3d structure prediction, especially of large rnas, still remains a significant challenge and there is still a great dema ... | 2015 | 25726459 |
| decolorization and biodegradation of remazol reactive dyes by clostridium species. | decolorisation and biodegradation efficacy of potential strains isolated from dyeing effluent collected from tirupur region, tamil nadu, india were studied in remazol reactive dyes. two potential strains clostridium butyricum (ei05) and clostridium acetobutylicum (ei25) identified by biochemical tests in our previous study were studied for their decolorising efficiency on various remazol reactive dyes (remazol blue rgb, remazol blue rr, remazol navy rgb and remazol orange rr). the synthetic dyes ... | 2016 | 28330087 |
| acetone-butanol-ethanol production from substandard and surplus dates by egyptian native clostridium strains. | one hundred and seven mesophilic isolates of clostridium were isolated from agricultural soils cultivated with different plants in assuit governorate, egypt. eighty isolates (out of 107) showed the ability to produce abe (acetone, butanol and ethanol) on t6 medium ranging from 0.036 to 31.89 g/l. the highest numbers of abe producing isolates were obtained from soil samples of potato contributing 27 isolates, followed by 18 isolates from wheat and 10 isolates from onion. on the other hand, there ... | 2015 | 25557787 |
| molecular basis of [fefe]-hydrogenase function: an insight into the complex interplay between protein and catalytic cofactor. | the precise electrochemical features of metal cofactors that convey the functions of redox enzymes are essentially determined by the specific interaction pattern between cofactor and enclosing protein environment. however, while biophysical techniques allow a detailed understanding of the features characterizing the cofactor itself, knowledge about the contribution of the protein part is much harder to obtain. [fefe]-hydrogenases are an interesting class of enzymes that catalyze both, h2 oxidati ... | 2016 | 23507618 |
| enhanced butanol production from cassava with clostridium acetobutylicum by genome shuffling. | to obtain strains exhibiting high levels of solvent tolerance and butanol production, wild type strains of clostridium acetobutylicum butanol-producing strain gx01 and lactobacillus mucosae butanol-tolerant strain m26 were subjected to mutagenesis combining n-methyl-n-nitro-n-nitrosoguanidine induction with genome shuffling. after four successive rounds of genome shuffling, the c. acetobutylicum shuffled strain gs4-3 showing greater levels of fermentation performances (such as secreting a higher ... | 2016 | 26925615 |
| synergistic dark and photo-fermentation continuous system for hydrogen production from molasses by clostridium acetobutylicum atcc 824 and rhodobacter capsulatus dsm 1710. | this study investigated synergistic dark and photo-fermentation using continuous fermentation system (cfs). the system relies on connecting several fermenters from bottom of one to top culture level of the next in a manner that allows for delaying movement of the substrate and thus for its full consumption. while h2 was collected, cfs allowed for moving liquid byproducts toward the outlet and hence continuous productivity. cfs could be efficiently used for: (1) continuous dark and photo-fermenta ... | 2017 | 28242562 |
| development of a rhodobacter capsulatus self-reporting model system for optimizing light-dependent, [fefe]-hydrogenase-driven h2 production. | the photosynthetic bacterium rhodobacter capsulatus normally photoproduces h2 as a by-product of its nitrogenase-catalyzed nitrogen-fixing activity. such h2 production, however, is expensive from a metabolic perspective, requiring nearly four times as many photons as the equivalent algal hydrogenase-based system (ghirardi et al., 2009 photobiological hydrogen-producing systems. chem soc rev 38(1):52-61). here, we report the insertion of a clostridium acetobutylicum [fefe]-hydrogenase and its thr ... | 2017 | 27531314 |
| high-efficient n-butanol production by co-culturing clostridium acetobutylicum and saccharomyces cerevisiae integrated with butyrate fermentative supernatant addition. | butanol is not only an important chemical intermediate and solvent in pharmaceutical and cosmetics industries, but also considered as an advanced biofuel. although species of the natural host clostridium have been engineered, butanol titers in the anaerobe seem to be limited by its intolerance to butanol less than 13 g/l. here we aimed to develop a technology for enhancing butanol production by a co-culture system with butyrate fermentative supernatant addition. first, when adding 4.0 g/l butyra ... | 2017 | 28337710 |
| integrated intracellular metabolic profiling and pathway analysis approaches reveal complex metabolic regulation by clostridium acetobutylicum. | clostridium acetobutylicum is one of the most important butanol producing strains. however, environmental stress in the fermentation process usually leads to a lower yield, seriously hampering its industrialization. in order to systematically investigate the key intracellular metabolites that influence the strain growth and butanol production, and find out the critical regulation nodes, an integrated analysis approach has been carried out in this study. | 2016 | 26879529 |
| enhancing butanol production under the stress environments of co-culturing clostridium acetobutylicum/saccharomyces cerevisiae integrated with exogenous butyrate addition. | in this study, an efficient acetone-butanol-ethanol (abe) fermentation strategy integrating clostridium acetobutylicum/saccharomyces cerevisiae co-culturing system with exogenous butyrate addition, was proposed and experimentally conducted. in solventogenic phase, by adding 0.2 g-dcw/l-broth viable s. cerevisiae cells and 4.0 g/l-broth concentrated butyrate solution into c. acetobutylicum culture broth, final butanol concentration and butanol/acetone ratio in a 7 l anaerobic fermentor reached th ... | 2015 | 26489085 |
| enhancing acetone biosynthesis and acetone-butanol-ethanol fermentation performance by co-culturing clostridium acetobutylicum/saccharomyces cerevisiae integrated with exogenous acetate addition. | acetone is the major by-product in abe fermentations, most researches focused on increasing butanol/acetone ratio by decreasing acetone biosynthesis. however, economics of abe fermentation industry strongly relies on evaluating acetone as a valuable platform chemical. therefore, a novel abe fermentation strategy focusing on bio-acetone production by co-culturing clostridium acetobutylicum/saccharomyces cerevisiae with exogenous acetate addition was proposed. experimental and theoretical analysis ... | 2016 | 26476171 |
| solvents production from a mixture of glucose and xylose by mixed fermentation of clostridium acetobutylicum and saccharomyces cerevisiae. | to overcome the xylose utilization defect in ethanol fermentation by wide-type saccharomyces cerevisiae and alleviate the carbon catabolite repression (ccr) in acetone-butanol-ethanol (abe) fermentation by clostridium acetobutylicum, a novel mixed fermentation of s. cerevisiae and c. acetobutylicum was developed. when s. cerevisiae was inoculated 24 h earlier than c. acetobutylicum ch02, a higher solvents yield was achieved with 0.41 g/g, compared to 0.38 g/g in abe fermentation, and when s. cer ... | 2015 | 26265395 |
| evaluation of fluorimetric ph sensors for bioprocess monitoring at low ph. | optical chemical sensors are the standard for ph monitoring in small-scale bioreactors such as microtiter plates, shaking flasks or other single-use bioreactors. the dynamic ph range of the so far commercially available fluorescent ph sensors applied in small-scale bioreactors is restricted to ph monitoring around neutral ph, although many fermentation processes are performed at ph < 6 on industrial scale. thus, two new prototype acidic fluorescence ph sensors immobilized in single-use stirred-t ... | 2015 | 25969385 |
| production of an acetone-butanol-ethanol mixture from clostridium acetobutylicum and its conversion to high-value biofuels. | clostridium acetobutylicum is a bacterial species that ferments sugar to a mixture of organic solvents (acetone, butanol and ethanol). this protocol delineates a methodology to combine solventogenic clostridial fermentation and chemical catalysis via extractive fermentation for the production of biofuel blendstocks. extractive fermentation of c. acetobutylicum is operated in fed-batch mode with a concentrated feed solution (500 grams per liter glucose and 50 grams per liter yeast extract) for 60 ... | 2015 | 25719271 |
| enhanced butanol production by eukaryotic saccharomyces cerevisiae engineered to contain an improved pathway. | compared with ethanol, butanol has more advantageous physical properties as a fuel, and biobutanol is thus considered a promising biofuel material. biobutanol has often been produced by clostridium species; however, because they are strictly anaerobic microorganisms, these species are challenging to work with. we attempted to introduce the butanol production pathway into yeast saccharomyces cerevisiae, which is a well-known microorganism that is tolerant to organic solvents. 1-butanol was found ... | 2015 | 25348391 |
| incorporation of nasutitermes takasagoensis endoglucanase into cell surface-displayed minicellulosomes in pichia pastoris x33. | in this study, the yeast pichia pastoris was genetically modified to assemble minicellulosomes on its cell surface by the heterologous expression of a truncated scaffoldin cipa from clostridium acetobutylicum. fluorescence microscopy and western blot analysis confirmed that cipa was targeted to the yeast cell surface and that ntegd, the nasutitermes takasagoensis endoglucanase that was fused with dockerin, interacted with cipa on the yeast cell surface, suggesting that the cohesin and dockerin d ... | 2014 | 24851815 |
| in situ extractive fermentation for the production of hexanoic acid from galactitol by clostridium sp. bs-1. | clostridium sp. bs-1 produces hexanoic acid as a metabolite using galactitol and enhanced hexanoic acid production was obtained by in situ extractive fermentation with clostridium sp. bs-1 under an optimized medium composition. for medium optimization, five ingredients were selected as variables, and among them yeast extract, tryptone, and sodium butyrate were selected as significant variables according to a fractional factorial experimental design, a steepest ascent experimental design, and a b ... | 2013 | 23830453 |
| metabolic engineering of candida utilis for isopropanol production. | a genetically-engineered strain of the yeast candida utilis harboring genes encoding (1) an acetoacetyl-coa transferase from clostridium acetobutylicum atcc 824, (2) an acetoacetate decarboxylase, and (3) a primary-secondary alcohol dehydrogenase derived from clostridium beijerinckii nrrl b593 produced up to 0.21 g/l of isopropanol. because the engineered strain accumulated acetate, isopropanol titer was improved to 1.2 g/l under neutralized fermentation conditions. optimization of isopropanol p ... | 2013 | 23674152 |